title: Adsorption of phytosterol ethoxylates on silica in an aprotic room-temperature ionic liquid.
abstract: The adsorption of a nonionic surfactant at a silica/room-temperature ionic liquid interface has been characterized on the basis of analytical data obtained through a combination of surface force measurements, in situ soft-contact atomic force microscope (AFM) images, and quartz crystal microbalance with dissipation monitoring (QCM-D) data. The surfactant employed in this study is a kind of phytosterol ethoxylate (BPS-20), and the ionic liquid selected here is aprotic 1-ethyl-3-methyl-imidazolium bis(trifluoromethylsulfonyl)imide (EmimTFSI). This ionic liquid spontaneously forms solvation layers on silica, being composed of an Emim(+) cation layer and EmimTFSI ion pair layers. The addition of BPS-20 disrupts these solvation layers and suggests a surfactant layer adsorbed at the interface. This is the first report demonstrating the adsorption of nonionic surfactants at the solid/aprotic ionic liquid interface.
authors.affiliation: Department of Pure and Applied Chemistry in Faculty of Science and Technology and Research Institute for Science and Technology, Tokyo University of Science, 2641 Yamazaki, Noda, Chiba 278-8510, Japan. k-sakai@rs.noda.tus.ac.jp
authors.forename: Kenichi
authors.initials: K
authors.lastname: Sakai
authors.forename: Yosuke
authors.initials: Y
authors.lastname: Onuma
authors.forename: Kanjiro
authors.initials: K
authors.lastname: Torigoe
authors.forename: Simon
authors.initials: S
authors.lastname: Biggs
authors.forename: Hideki
authors.initials: H
authors.lastname: Sakai
authors.forename: Masahiko
authors.initials: M
authors.lastname: Abe